Wavelength division multiplexing module

ABSTRACT

A telecommunications module includes an optical wavelength division multiplexer/demultiplexer configured to demultiplex a first optical signal input into the telecommunications module into a plurality of different wavelengths, a fiber optic splitter configured to split a second optical signal input into the telecommunication module into a plurality of optical signals, and a plurality of optical add/drop filters, each of the optical add/drop filters configured to combine one of the optical signals that has been split by the fiber optic splitter and one of the wavelengths that has been demultiplexed by the optical wavelength division multiplexer/demultiplexer into a combination output signal that is output from the telecommunications module.

CROSS REFERENCE TO RELATED APPLICATION

This application is a continuation of U.S. patent application Ser. No.15/706,969, filed Sep. 18, 2017; which is a continuation of U.S. patentapplication Ser. No. 14/930,332, filed Nov. 2, 2015, now U.S. Pat. No.9,768,900; which is a continuation of U.S. patent application Ser. No.14/157,644, filed Jan. 17, 2014, now U.S. Pat. No. 9,97,346; which is acontinuation of U.S. patent application Ser. No. 13/362,210, filed Jan.31, 2012, now U.S. Pat. No. 8,660,429; which is a continuation of U.S.patent application Ser. No. 12/360,719, filed Jan. 27, 2009, now U.S.Pat. No. 8,107,816; which application claims the benefit of U.S.Provisional Patent Application Ser. No. 61/024,450, filed Jan. 29, 2008,which applications are hereby incorporated by reference in theirentireties.

FIELD

The present disclosure generally relates to fiber optictelecommunications equipment. More specifically, the present disclosurerelates to modules for housing fiber optic telecommunications equipment.

BACKGROUND

In fiber optic telecommunications systems, it is common for opticalfibers of transmission cables to be split into multiple strands, eitherby optical splitting of a signal carried by a single stranded cable orby fanning out the individual fibers of a multi-strand cable. Further,when such systems are installed, it is known to provide excess capacityin the installations to support future growth and utilization of thefibers. Often in these installations, modules including splitters orfanouts are used to provide the connection between transmission fibersand customer fibers. To reduce the cost and complexity of the initialinstallation and still provide options for future expansion, a modulemounting chassis capable of mounting multiple modules may be used insuch an installation.

While a chassis may accept several modules, the initial installation mayonly include fewer modules mounted in the chassis, or enough to servecurrent needs. These chassis may be configured with limited access toone or more sides, or may be mounted in cramped locations. In addition,some of these chassis may be pre-configured with the maximum capacity oftransmission cables to accommodate and link to modules which may beinstalled in the future. Since it is desirable to have access tocomponents within the chassis for cleaning during the installation of anew module, some provision or feature of the chassis will desirablypermit a user to access and clean the connectors of thesepre-connectorized and pre-installed transmission cables.

It is also desirable for the chassis to be configured to ensure thatmodules are installed correctly and aligned with other components withinthe chassis to mate with the pre-connectorized and pre-installedtransmission cables.

In fiber-optic communications, it is also common for optical signals oftransmission cables to be multiplexed. Wavelength division multiplexing(WDM) is a technology which multiplexes multiple optical carrier signalson a single optical fiber by using different wavelengths of laser lightto carry different signals. This allows for a multiplication incapacity, in addition to making it possible to perform bidirectionalcommunications over one strand of fiber.

A WDM system uses a multiplexer at the transmitter to join signalstogether and a demultiplexer at the receiver to split them apart. Withthe right type of fiber, it is possible to have a device that does bothsimultaneously, and can function as an optical add-drop multiplexer. WDMsystems allow expansion of the capacity of the network without layingmore fiber.

WDM systems are divided in different wavelength patterns: 1)conventional WDM; 2) dense WDM (DWDM); and 3) coarse WDM (CWDM). WDM,DWDM and CWDM are based on the same concept of using multiplewavelengths of light on a single fiber, but differ in the spacing of thewavelengths, number of channels, and the ability to amplify themultiplexed signals in the optical space.

In certain telecommunications applications, it might be desirable tocombine wavelength division multiplexing technology with fiber opticsignal splitting technology.

SUMMARY

The present invention relates to telecommunications equipment thatcombines wavelength division multiplexing technology and fiber opticsignal splitting technology and packages it in a modular format. Themodule of the present disclosure includes an input for inputting a fiberoptic signal to be split into multiple strands, an input for inputting afiber optic signal to be demultiplexed into different wavelengths oflaserlight, and an output for outputting a combination signal wherein asplit signal and a demultiplexed wavelength are combined into a singleoutput fiber.

According to one aspect, the module includes within the interior anoptical multiplexer/demultiplexer, a fiber optic splitter, and anoptical device for combining a split signal and a demultiplexedwavelength into an output fiber.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are incorporated in and constitute apart of the description, illustrate several aspects of the inventivefeatures and together with the detailed description, serve to explainthe principles of the disclosure. A brief description of the drawings isas follows:

FIG. 1 is an exploded view of a fiber optic wavelength-divisionmultiplexing (WDM) module having features that are examples of inventiveaspects in accordance with the present disclosure;

FIG. 2 illustrates the WDM module of FIG. 1 in a fully assembledconfiguration including the input and the output signals going into anda coming out of, respectively, the module;

FIG. 3 is a right side view of the WDM module of FIG. 1;

FIG. 4 is a left side view of the WDM module of FIG. 1;

FIG. 5 is an exploded view of a module housing of the WDM module of FIG.1;

FIG. 6 is a perspective view of a splice holder/cable managementstructure of the WDM module of FIG. 1;

FIG. 7 is a bottom view of the splice holder/cable management structureof FIG. 6;

FIG. 8 is a front view of the splice holder/cable management structureof FIG. 6;

FIG. 9 is a perspective view of another cable management structure ofthe WDM module of FIG. 1;

FIG. 10 is a top view of the cable management structure of FIG. 9;

FIG. 11 is a front view of the cable management structure of FIG. 9;

FIG. 12 is a schematic view illustrating the fiber optic circuit of theWDM module of FIG. 1;

FIG. 13 is a diagram illustrating a fiber optic splitter configured foruse in the WDM module of FIG. 1;

FIG. 14 is a diagram illustrating a multiplexer chip configured for usein the WDM module of FIG. 1;

FIG. 15 is a diagram illustrating an optical add/drop filter configuredfor use in the WDM module of FIG. 1, the add/drop filter configured tocombine a split signal and a demultiplexed wavelength into a singleoutput fiber;

FIG. 16 is an exploded view of an input connection for inputting asignal into the splitter of the WDM module of FIG. 1;

FIG. 17 illustrates the input connection of FIG. 16 in a fully assembledconfiguration;

FIG. 18 illustrates an input connection in a fully assembledconfiguration for inputting a signal into the multiplexer chip of theWDM module to be demultiplexed into different wavelengths of laserlight;

FIG. 19 is a diagram illustrating the input connection of FIG. 17 withthe fiber optic circuit of the fiber optic splitter configured for usewith the WDM module;

FIG. 20 is a diagram illustrating the input connection of FIG. 18 withthe fiber optic circuit of the multiplexer chip configured for use withthe WDM module;

FIG. 21 is an exploded view of an output connection for outputting asignal from the WDM module of FIG. 1;

FIG. 22 illustrates the output connection of FIG. 21 in a fullyassembled configuration;

FIG. 23 illustrates an example routing of a fiber optic cable from aninput connection of the WDM module to an input location of the fiberoptic splitter within the WDM module;

FIG. 24 illustrates an example routing of a fiber optic cable from anoutput location of the fiber optic splitter to an input location of anoptical add/drop filter that is configured to combine a split signal anda demultiplexed wavelength into a single output fiber;

FIG. 25 illustrates an example routing of a fiber optic cable from aninput connection of the WDM module to an input location of themultiplexer chip within the WDM module;

FIG. 26 illustrates an example routing of a fiber optic cable from anoutput location of the multiplexer chip to an input location of anoptical add/drop filter that is configured to combine a split signal anda demultiplexed wavelength into a single output fiber;

FIG. 27 illustrates an example routing of a fiber optic cable from anoutput location of the optical add/drop filter that is configured tocombine a split signal and a demultiplexed wavelength to an outputconnection of the WDM module; and

FIG. 28 is a diagram illustrating an example positioning of a pluralityof output connections of the WDM module among a plurality of fillercrimp tubes.

DETAILED DESCRIPTION

Reference will now be made in detail to exemplary aspects of the presentdisclosure which are illustrated in the accompanying drawings. Whereverpossible, the same reference numbers will be used throughout thedrawings to refer to the same or similar parts.

FIGS. 1-4 illustrate a telecommunications module 10 having features thatare examples of inventive aspects in accordance with the presentdisclosure. Since one of the telecommunications equipment housed by themodule 10 is a fiber optic wavelength divisionmultiplexer/demultiplexer, the telecommunications module 10 may also bereferred to herein as a fiber optic wavelength division multiplexing(WDM) module 10. The WDM module 10 is configured to be inserted within atelecommunications chassis similar to the chassis shown and described incommonly-owned U.S. Pat. No. 7,536,075, the disclosure of which isincorporated herein by reference in its entirety. As will be describedin further detail below, the WDM module 10 is also configured to beinserted into the telecommunications chassis in a similar manner to thatshown and described in the U.S. patent application Ser. No. 11/975,905.

The WDM module 10 of the present disclosure is configured to power splitan input signal into a plurality of signals. The WDM module 10 is alsoconfigured to demultiplex a second input signal into a plurality ofwavelengths. An optical device 22 (e.g., an optical add/drop filter, asingle channel filter, etc.) within the module 10 is configured tocombine one of the power split signals and one of the demultiplexedwavelengths into a combination output signal that is output through themodule 10. The powersplitting function, the demultiplexing function andthe signal combination function are all performed within the module 10.

Referring to FIG. 1, the WDM module 10 is shown in an explodedorientation. WDM module 10 includes a module housing 12 that includes amain housing portion 14 and a removable cover 16. The module housing 12including the main housing portion 14 and the removable cover 16 isillustrated separately in FIG. 5, without the internal components of themodule 10.

Still referring to FIG. 1, the WDM module 10 is configured to house afiber optic splitter 18, a multiplexer/demultiplexer chip 20, and aplurality of optical devices 22 configured to combine a split signal anda demultiplexed wavelength into a single output signal. According to oneembodiment, the optical devices 22 that are configured to combine asplit signal and a demultiplexed wavelength into a single output signalmay be optical add/drop filters. Optical add/drop filters and their usesare known in the art. The optical add/drop filters may also be calledsingle channel filters. Other types of devices performing the samefunction are possible.

The fiber optic splitter 18 is adapted to power split a first inputfiber optic signal entering the module 10 into multiple strands. Themultiplexer/demultiplexer chip 20 is configured to demultiplex a secondinput fiber optic signal entering the module 10 into differentwavelengths of laserlight. Each of the optical devices 22 (e.g.,add/drop filters) is configured to combine one of the split signals andone of the demultiplexed wavelengths into a single output fiber. Each ofthe combination signals are then output from the module 10. In theembodiment shown, the fiber optic splitter 18 is a 1×8 splitter and themultiplexer/demultiplexer 20 is an 8-channel chip. Accordingly, in theembodiment of the module 10 shown, 1 splitter input signal and 1multiplexer input signal get output as 8 separate combination signals.

A fiber optic circuit diagram of the WDM module 10 of FIGS. 1-4 is shownin FIG. 12. FIG. 13 diagrammatically illustrates the fiber opticsplitter 18 configured for use in the WDM module 10. FIG. 14diagrammatically illustrates the multiplexer chip 20 configured for usein the WDM module 10. FIG. 15 diagrammatically illustrates one of theadd/drop filters 22 configured for use in the WDM module 10 of FIG. 1,wherein the add/drop filter 22 is configured to combine a split signaland a demultiplexed wavelength into an output signal.

According to one example embodiment shown in FIG. 12, a signal inputinto the fiber optic splitter 18 gets split into 8 separate signals,each separate signal being the same as the original input signal. Itshould be noted that in other embodiments, the fiber optic splitter 18may power split the signal into different power levels, rather than intothe same signal. From an output 24 of the splitter 18, each of the splitsignals get spliced into an input 26 (i.e., PASS leg) of each of theadd/drop filters 22. Likewise, a signal input into the multiplexer chip20 gets demultiplexed into 8 different wavelengths. Each wavelength getsoutput from the multiplexer chip 20 as a separate signal and is splicedinto another input 28 (i.e., REF leg) of the each of the add/dropfilters 22. The signals from the splitter 18 and the multiplexer chip 20are combined at the add/drop filters 22 and output from the add/dropfilters 22 (e.g., at COM leg) as 8 combination signals.

FIG. 2 illustrates the WDM module 10 with the two input signal cables30, 32 going into the module 10 and the eight combination output signalcables (each one designated as “34”) coming out. As shown, the inputcables 30, 32 and the output cables 34 may be connectorized and beforwarded on to appropriate locations through fiber optic adapters 36.As shown in FIG. 2, the module housing 12 includes a cable exit 38 foroutputting the combination fiber optic signals out of the module 10 andto customers.

Referring back to FIG. 1, the WDM module 10 includes a number of cablemanagement/routing features for correctly orienting the cables withinthe module 10, as will be described in further detail below. One suchfeature is a splice holder/cable management structure 40 that isconfigured to house the plurality of fiber optic splices 42 within themodule 10 and also route fiber optic cables through the module 10 (shownin further detail in FIGS. 6-8). Another cable routing feature is acable management structure 44. In the depicted embodiment, the cablemanagement structure is shown located between the fiber optic splitter18 and the add/drop filters 22 (shown in further detail in FIGS. 9-11).In other embodiments, the cable management structure 44 could be locatedbetween the fiber optic splitter 18 and the bottom wall 54 of the module10. A fiber retainer 46 that is removably mounted to the main housingportion 14 of the module housing 12 is also shown in FIG. 1. The fiberretainer 46 helps keep cables spooled around a first radius limiter 48within the main housing 14 of the module 10.

FIGS. 2-4 illustrate the module 10 in a fully assembled configurationwith the cover 16 mounted on the main housing portion 14.

FIG. 5 illustrates the housing 12 of the module 10 in isolation, withthe internal features of the module 10 removed therefrom. Referring toFIG. 5, the main housing portion 14 defines a first sidewall 50extending between a top wall 52, a bottom wall 54, a rear wall 56, and afront wall 58. Removable cover 16 defines a second sidewall 60 of themodule housing 12 and closes off an open side 62 of the module mainhousing portion 14. Cover 16 is mounted to main housing portion 14 byfasteners through fastener holes 64 in the cover 16 and fastener mounts66 defined on main housing portion 14. The cover 16 may include a label68 placed thereon with indicia relating to the module 10 (see FIGS. 1and 3).

The main housing portion 14 defines a top mounting flange 70 and abottom mounting flange 72 of the WDM module 10 extending from the topand bottom walls 52, 54, respectively. As discussed previously, the WDMmodule 10 of the present application is configured for insertion into achassis similar to the one described in U.S. patent application Ser. No.11/975,905 and in a similar manner to that described therein. As such,similar to the modules and the chassis described in U.S. patentapplication Ser. No. 11/975,905, the bottom flange 72 and acorresponding slot on the chassis are smaller in size than top flange 70and the corresponding top slot on the chassis. Bottom slot of thechassis is sized such that, while bottom flange 72 fits into the bottomslot of the chassis, the larger top flange 70 does not fit. This ensuresthat the WDM module 10 is positioned within a front opening of a chassisin a particular desired orientation to correctly position the cableinputs and the outputs relative to the chassis.

It should also be noted that while the housing 12 of the WDM module 10of the present application is configured similarly to those of themodules shown in described in U.S. patent application Ser. No.11/975,905 for mounting purposes, the WDM module 10 of the presentapplication has certain differences. The WDM module housing 12 of thepresent application has the depth of two of the modules of U.S. patentapplication Ser. No. 11/975,905. As such, the WDM module 10 of thepresent application occupies two mounting locations within a chassissuch as the chassis shown in U.S. patent application Ser. No.11/975,905.

Still referring to FIG. 5, the rear wall 56 of main housing portion 14includes a curved portion 74 configured to provide bend radiusprotection to cables within interior of the module 10. Similar tomodules of U.S. patent application Ser. No. 11/975,905, the rear wall 56of main housing 14 includes an inset portion 76. The inset portion 76might be used to accommodate a pair of fiber optic connectors protrudingout of the rear wall 56, if, for example, a rear input configuration isdesired instead of a front input configuration. It should be noted thatin the depicted embodiment, the WDM module 10 includes a front inputconfiguration. Thus, the slots 78 for receiving fiber optic connectorsat the rear wall 56 may be covered with inserts 80 (see FIG. 5). In U.S.patent application Ser. No. 11/975,905, the modules are shown with arear input configuration wherein rear fiber optic connectors protrudefrom the rear wall at the inset portion of the module housing. As notedbefore, a rear input configuration is certainly one option for the WDMmodule 10 of the present application. In such a configuration, fiberoptic connectors protruding rearwardly from rear wall 56 would mate withfiber optic adapters of adapter assemblies that are mounted within thechassis.

Still referring to FIG. 5, in the depicted embodiment, the inputconnections 82, 84 are provided at the front of the module main housing14. FIG. 16 illustrates an exploded view of an input connection 82 forinputting a signal into the splitter 18 of the WDM module 10 and FIG. 17illustrates the input connection 82 of FIG. 16 in a fully assembledconfiguration. FIG. 19 is a diagram illustrating the input connection 82with the fiber optic splitter 18 configured for use in the WDM module10.

FIG. 18 illustrates a fully assembled view of the input connection 84for inputting a signal into the multiplexer chip 20 of the WDM module 10to be demultiplexed into different wavelengths of laserlight. FIG. 20 isa diagram illustrating the input connection 84 with the multiplexer chip20 configured for use in the WDM module 10.

As shown in FIGS. 16-20, each input connection 82, 84 (whether for thefiber optic splitter 18 or the multiplexer chip 20) includes a boot 86that mates with a crimp element 88. The crimp element 88 defines acircumferential notch 90 (i.e., recessed portion). The circumferentialnotch 90 is slidably inserted into a slot 92 defined on an insert piece59 that is fastened to the front wall 58 of the main housing portion 14with fasteners (see FIGS. 1 and 5). The crimp elements 88 of the inputconnections 82, 84 are captured by the cover 16 when the cover 16 ismounted on the main housing 14.

As mentioned previously, the embodiment of the WDM module 10 illustratedincludes the cable exit 38 at the front of module main housing 14 (seeFIG. 1). The cable exit 38 is slidably mounted to main housing 14 of theWDM module 10 and is captured by the cover 16 when cover 16 is mountedto main housing 14. The cable exit 38 defines a protruding rear lip 94that is slidably inserted into a slot 96 defined around a front aperture98 defined at the front wall 58 for accommodating the cable exit 38. Thecable exit 38 permits telecommunications cables within the module 10 tobe directed outside of the module 10. The cable exit 38 is preferablysized to fit within the profile of the WDM module 10 to preserve thedensity of a telecommunications assembly having a plurality of modules10 mounted adjacent to each other.

The front wall 58 of the module main housing 14 is angled with regard toa front opening of a chassis, which may aid in directing cables enteringand exiting the WDM module 10 toward a desired location. In otherembodiments, front walls could be made generally parallel to a front ofchassis within the scope of the present disclosure.

As noted above, the WDM module 10 of the present application includessimilar features to those modules shown and described in U.S. patentapplication Ser. No. 11/975,905 for mounting purposes. As such, the mainhousing portion 14 includes an integrally formed flexible latch 100(i.e., cantilever arm) that is adapted to engage a portion of a chassisto hold module 10 within a front opening of the chassis. Flexible latch100 also deflects to permit withdrawal of the module 10 from a chassis.The flexible latch 100 of the module 10 is constructed similarly to thatof modules of U.S. patent application Ser. No. 11/975,905 and includes afinger grip tab 102, a front latching tab 104 and a rear latching tab106 that cooperate with a bulkhead at a mounting location of a chassis.The WDM module 10 also includes a fixed grip tab 108 opposing andadjacent to flexible latch 100 to aid removal of module 10 from chassis.Fixed grip tab 108 is preferably positioned on module 10 opposite latch100 so that a user may apply opposing force on latch 100 and fixed griptab 108 to securely grasp module 10 and remove it from a chassis withtwo adjacent fingers of the hand. The insertion of the WDM module 10into a chassis is similar to that of modules described in U.S. patentapplication Ser. No. 11/975,905.

Now referring back to FIG. 5, within interior of main housing 14, moduleincludes a first radius limiter 48 adjacent the curved portion 74 ofrear wall 56 of main housing 14. The WDM module 10 includes a secondradius limiter 110 adjacent front wall 58 of housing 12 near the cableexit 38. As will be discussed in further detail below, the radiuslimiters 48, 110 provide bend-protection to fiber cables within themodule 10 while providing cable management/routing functionality.

Still referring to FIG. 5, the module main housing 14 also includesintegrally formed crimp holders 112 (e.g., slots) adjacent the frontwall 58 of housing 14 underneath the second radius limiter 110. Crimpelements 114 (see FIGS. 21-22) crimped to the ends of cables that areextending from the output locations 116 of the add/drop filters 22 areslidably received into the crimp holders 114. Crimp elements 114 includesquare flanges 118 between which are defined recessed portions 120. Thecrimp holders 112 include complementary structure to the crimp elements114 such that once the crimp elements 114 are slidably inserted into thecrimp holders 112, the crimp elements 114 are prevented from moving in alongitudinal direction due to the flanges 118. Once slidably inserted,crimp elements 114 are held in place by the cover 16 that is mounted onthe module main housing 14. The assembly of an output connection 122 foroutputting a signal from the WDM module 10 is shown in detail in FIGS.21 and 22. A crimp element 114 is crimped and terminated to a cable in amanner commonly known in the art.

In the embodiment shown, there are four crimp holding slots 112, eachslot 112 being able to accommodate up to eight crimp elements 114 (seeFIG. 28). Since there are eight combination output signals in theembodiment of the WDM module 10 shown, the output cables 34 occupy eightcrimp holding positions 124. The rest of the positions 124 may be filledwith dummy crimp elements or inserts/fillers that are not connected tocables, making sure the crimp elements 114 crimped to active outputcables 34 do not slide out of the slots 112. In FIG. 28, one examplepositioning of a plurality of “active” crimp elements 114 among fillercrimp elements is shown.

In the embodiment of the module shown, the crimp holders 112 provide thecapacity for up to thirty-two crimp elements 114 connected to outputcables 34. Thus, the WDM module 10 of the present disclosure couldhouse, if desired, a 1×32 fiber optic splitter and a 32 channelmultiplexer. Also, the configuration of the module housing 12 cancertainly be modified to accommodate other number of inputs or outputs,as desired. In addition, other complementary shapes between the crimpelements 114 and the crimp holders 112 are possible to provide aslidable fit and to prevent axial movement of the crimp elements 114within the crimp holders 112.

Still referring to FIG. 5, the first radius limiter 48 defines a curvedwall 126. The curved wall 126 includes a first end 128 and a second end130. The first and second ends 128, 130 of the curved wall 126 act asguides in positioning the multiplexer chip 20 within the main housing 14(see FIGS. 23-27). Also as shown in FIGS. 23-27, the bottom wall 54 ofthe module main housing 14, the ends 128, 130 of the curved wall 126 ofthe first radius limiter 48, the splice holder 40 adjacent the top wall52 of the module main housing 14 and a tab 132 extending from the crimpholding structure 112 define a frame structure around the multiplexerchip 20 for correctly positioning the multiplexer chip 20 within theinterior of the main housing portion 14. As shown in FIGS. 1 and 23-27,once the multiplexer chip 20 is placed within the main housing portion14, the fiber optic splitter 18 and the add/drop filters 22 are placednext adjacent thereto and held within the module 10 against the chip 20by the removable cover 16.

As noted above, the fiber retainer 46 may be placed on the main housingportion 14 to keep cables wrapped around the first radius limiter 48.The fiber retainer 46 is planar and includes a circular shape to matchthe contour of the curved portion 74 of the rear wall 56 of the mainhousing 14. The fiber retainer 46 includes three tabs 134 positionedaround the periphery. The three tabs 134 are placed within slots 136formed around the curved portion 74 of the rear wall 56. The fiberretainer 46 includes a circular opening 138 which accommodates a portionof the first radius limiter 48 that protrudes through the opening 138.When the fiber retainer 46 is placed on the main housing portion 14, itlies flush with the main housing portion 14 and is held thereagainst bythe cover 16.

FIG. 5 also illustrates the cover 16 of the WDM module 10. The cover 16is configured to be fastened to the module main housing portion 14. Thecover 16 defines a similar contour as the main housing portion 14 andcaptures the internal components within the module 14. The cover 16includes protruding portions 140 defined around the periphery and slots142 defined between the protruding portions 140 that intermate withcorresponding structures located around the periphery of the mainhousing 14 for correctly placing the cover 16 onto the main housing 14.

FIGS. 6-8 illustrate the splice holder/cable management structure 40 ofthe WDM module 10 in detail. The splice holder/cable managementstructure 40 is configured to be placed within the module 10 between thetop wall 52 and the multiplexer chip 20 (see FIGS. 1 and 23-27). Thesplice holder 40 includes a first wall 144 and second and third integralsidewalls 146, 148 extending perpendicularly from the first wall 144.The second and third sidewalls 146, 148 define a channel 150thereinbetween for guiding fiber optic cables therethrough. When thesplice holder/cable management structure 40 is placed within the module10, the third wall 148 rests against the multiplexer chip 20 (see FIGS.23-27). And, when mounted, the second wall 146 and the top wall 52 ofthe main housing portion 14 of the module 10 define a pocket 152 forplacing the fiber optic splice elements 42 therein. The second wall 146keeps the fiber optic splice elements 42 in the pocket 152 separatedfrom the fiber optic cables passing through the channel 150 definedbetween the second and third sidewalls 146, 148. In this manner, anyepoxy residue remaining in the splice area is kept away from the cablespassing through the channel 150.

As will be discussed in further detail below, when the module input 82for the splitter 18 is first routed to the fiber optic splitter input154 (see FIG. 23), the cable may pass through the pocket 152, over thesplice elements 42. Similarly, the module input 84 for the multiplexerchip 20 may pass through the pocket 152, over the splice elements 42,when being routed to the input location 158 of the multiplexer chip (seeFIG. 25).

Still referring to FIGS. 6-8, the third wall 148 of the spliceholder/cable management structure 40 may include an inset portiondefined by a notch 160 for accommodating fiber optic cables wrappedaround a spool 162 defined by the first radius limiter 48. The notch 160on the third wall 148 allows for expansion of fiber optic cables aroundthe spool 162.

FIGS. 9-11 illustrate the cable management structure 44 of the WDMmodule 10. The cable management structure 44 is configured to be placedinto the module 10 after the placement of the multiplexer chip 20. Inone embodiment, the cable management structure 44 is configured to belocated between the fiber optic splitter 18 and the add/drop filters 22.As mentioned previously, in other embodiments, the cable managementstructure 44 may be located between the fiber optic splitter 18 and thebottom wall 54 of the module housing 14. The cable management structure44 includes a U-shaped configuration with a first wall 164 and integralsecond and third sidewalls 166, 168 defining a channel 170thereinbetween. The channel 170 guides fiber optic cables therethroughwhen routed within the module 10 as will be discussed in further detailbelow.

Now referring back to FIG. 1, when the module 10 is assembled, themultiplexer chip 20 is placed into the main housing 14 first. The fiberoptic splitter 18 and the add/drop filters 22 are placed after themultiplexer chip 20 with the splitter 18 being separated from theadd/drop filters 22 by the cable management structure 44. As notedpreviously, the cable management structure 44 may be located between thesplitter 18 and the bottom wall 54 of the main housing 14. Spliceelements 42 are located adjacent the top wall 52 of the main housing 14and are separated from the multiplexer chip 20 by the spliceholder/cable management structure 40. The fiber retainer 46 is placed onthe first radius limiter 48 after the fiber cables have been routed tokeep the fiber cables wrapped around the spool 162 of the first radiuslimiter 48. The cover 16 holds the internal components of the module 10within the housing 12.

The WDM module 10 is shown in FIGS. 23-27 with the cover 16 and thefiber retainer 46 removed from the main housing portion 14 to illustratethe internal components and the routing of the cables therein. It shouldbe noted that the routing of the cables illustrated in FIGS. 23-27represents simply one example arrangement for the depicted module 10 andother arrangements are certainly possible.

In FIG. 23, an example routing arrangement of a first fiber optic cable172 from an input location 82 of the WDM module 10 to an input location154 of the fiber optic splitter 18 within the WDM module 10 isillustrated. A first cable 172 extends from the input connectionlocation 82 of the module 10 upwardly toward the splice holder/cablemanagement structure 40 and through the pocket 152 defined at the splicelocation, over the splice elements 42 (not shown in FIG. 23). From thesplice holder/cable management structure 40, the first cable 172 extendsdownwardly and around the first radius limiter 48 and is spooled aroundthe first radius limiter 48 as many times as necessary. After leavingthe first radius limiter 48, the first cable 172 extends toward thefront of the module 10 upwardly and around the second radius limiter110. From the second radius limiter 110, the first cable 172 extendsdownwardly and to the input location 154 of the fiber optic splitter 18.The fiber optic splitter 18 splits the optical signal into a pluralityof signals. In the given embodiment, a 1×8 splitter is used, and, thusthe signal from the first cable 172 may be split into eight signals.

It should be noted that various different types of fiber optic splittersmay be used within the module 10. According to one embodiment, the fiberoptic splitters may split an input signal into a plurality of the samesignals. In other embodiments, fiber optic splitters that split theinput signal into different power levels (i.e., different ratios),rather than into the same signal, may be used.

In FIG. 24, an example routing of a fiber optic cable 174 from an outputlocation 24 of the fiber optic splitter 18 to an input location 26 of anadd/drop filter 22 that is configured to combine a split signal and ademultiplexed wavelength into a single output signal is illustrated. Itshould be noted that only one of the eight fiber cables 174 from thesplitter 18 to the add/drop filter 22 is illustrated for claritypurposes. Other seven of the split signals carried by seven other fibercables 174 would follow a similar path to the one that will bedescribed.

Referring to FIG. 24, the second cable 174 extends from the outputlocation 24 of the splitter 18 and upwardly around the first radiuslimiter 48. The second cable 174 is spooled around the first radiuslimiter 48 as many times as needed. From the first radius limiter 48,the second cable 174 starts to extend toward the splice holder/cablemanagement structure 40 and is spliced at the splice location to a thirdcable 176. The third cable 176 extends toward the front of the module 10from the splice location and around the second radius limiter 110. Fromthe second radius limiter 110, the third cable 176 extends downwardlyand through the channel 170 formed by the cable management structure 44located between the splitter 18 and the add/drop filters 22 and towardthe rear of the module 10. From the channel 170, the third cable 176goes upwardly around the first radius limiter 48 as many times as neededand through the channel 150 defined by the splice holder/cablemanagement structure 40 toward the front of the module 10. From thesplice holder/cable management structure 40, the third cable 176 goesaround the second radius limiter 110 once again and downwardly to theinput location 26 of the add/drop filter 22 (i.e., the PASS leg of thefilter 22).

In FIG. 25, an example routing of a fiber optic cable 178 from an inputlocation 84 of the WDM module 10 to an input location 158 of themultiplexer chip 20 within the WDM module 10 is illustrated.

Referring to FIG. 25, the fourth cable 178 extends from the inputconnection 84 of the module 10 upwardly toward the splice holder/cablemanagement structure 40 and through the pocket 152 defined at the splicelocation, over the splice elements 42 (not shown in FIG. 25). Fromthere, the fourth cable 178 extends downwardly and around the firstradius limiter 48 and is spooled around the first radius limiter 48 asmany times as needed. After leaving the first radius limiter 48, thefourth cable 178 ends up at the input location 158 of the multiplexerchip 20. The multiplexer chip 20 demultiplexes the optical signalcarried by the fourth cable 178 into different wavelengths oflaserlight. In the given embodiment, an 8-channel multiplexer chip isused, and, thus, the signal from the fourth cable 178 will bedemultiplexed into eight different wavelengths.

In FIG. 26, an example routing of a fiber optic cable 180 from an outputlocation 182 of the multiplexer chip 20 to an input location 28 of anadd/drop filter 22 that is configured to combine a split signal and ademultiplexed wavelength into a single output signal is illustrated. Itshould be noted that routing of only one of the eight fiber cables 180from the multiplexer chip 20 to the add/drop filter 22 is illustratedfor clarity purposes. Other seven of the cables 180 carrying the otherseven demultiplexed wavelengths would follow a similar path to the onethat will be described.

Referring to FIG. 26, the fifth cable 180 extends from the outputlocation 182 of the multiplexer chip 20 and upwardly and around thesecond radius limiter 110. From the second radius limiter 110, the fifthcable 180 extends toward the rear of the module 10 through the channel150 defined by the splice holder/cable management structure 40. From thesplice holder/cable management structure 40, the fifth cable 180 extendsdownwardly around the first radius limiter 48 as many times as needed.From the first radius limiter 48, the fifth cable 180 extends toward thefront of the module 10 through the channel 170 formed by the cablemanagement structure 44. From the cable management structure 44, thefifth cable 180 extends upwardly toward the second radius limiter 110and around the second radius limiter 110. From the second radius limiter110, the fifth cable 180 extends toward the splice holder/cablemanagement structure 40 and is spliced at the splice location to a sixthcable 184. The sixth cable 184 extends from the splice location towardthe rear of the module 10 and around the first radius limiter 48. Thesixth cable 184 is spooled around the first radius limiter 48 as manytimes as needed. From the first radius limiter 48, the sixth cable 184extends toward the front of the module 10 to the input location 28 ofthe add/drop filter 22 (i.e., REF leg of the filter 22).

In FIG. 27, an example routing of a fiber optic cable 186 from an outputlocation 116 of the add/drop filter 22 (i.e., COM leg of filter 22) thatis configured to combine a split signal and a demultiplexed wavelengthto an output signal of the WDM module 10 is illustrated.

Referring to FIG. 27, the seventh cable 186 carrying a combinationsignal extends from the output 116 of the add/drop filter 22 toward therear of the module 10. The seventh cable 186 extends upwardly around thefirst radius limiter 48 and is spooled around the first radius limiter48 as many time as needed. From the first radius limiter 48, the seventhcable 186 extends toward the front of the module 10 through the channel150 defined by the splice holder/cable management structure 40. From thesplice holder/cable management structure 40, the seventh cable 186 isled to the crimp holders 112 of the module 10 and is crimped to a crimpelement 114. The eighth cable 34 (i.e., output cable 34) extends fromthe other end of the crimp element 114 to the cable exit 38 of themodule 10. It should be noted that the routing for only one of thecables going from the add/drop filter output 116 to the module outputhas been described for clarity purposes. There are eight add/dropfilters 22 for combining a split signal and a demultiplexed wavelength.Each of the cables extending from each add/drop filter output 116 to themodule exit 38 may follow a similar path to that described above.

As noted above, the routing of the fiber optic cables within module 10as shown in FIGS. 23-27 is only one example and other ways of routingthe cables within the module 10 are possible.

As noted previously, according to one embodiment, the WDM module 10 mayhouse an 8-channel wavelength division multiplexing chip. According toanother embodiment, the WDM module 10 may house a 4-channel wavelengthdivision multiplexing chip. According to another embodiment, the WDMmodule 10 may house a 16-channel wavelength division multiplexing chip.In other embodiments, the module 10 may house other types of wavelengthdivision multiplexing chips. In all the embodiments, the WDM module 10may house fiber optic splitters that are configured to split a signalinto a number of signals corresponding to the number of demultiplexedwavelengths. The fiber optic splitters used may power split the signalinto the same signals or into different power levels/ratios.

The disclosures of the following U.S. Patents are also incorporatedherein by reference in their entirety: U.S. Pat. No. 5,363,465, issuedNov. 8, 1994, entitled FIBER OPTIC CONNECTOR MODULE; U.S. Pat. No.5,317,663, issued May 20, 1993, entitled ONE-PIECE SC ADAPTER; U.S. Pat.No. 7,376,322, issued May 20, 2008, entitled FIBER OPTIC MODULE ANDSYSTEM INCLUDING REAR CONNECTORS; U.S. Pat. No. 7,400,813, issued July15, 2008, entitled FIBER OPTIC SPLITTER MODULE; U.S. Pat. No. 7,376,323,issued May 20, 2008, entitled FIBER OPTIC ADAPTER MODULE; and U.S. Pat.No. 7,346,254, issued Mar. 18, 2008, entitled FIBER OPTIC SPLITTERMODULE WITH CONNECTOR ACCESS.

The above specification, examples and data provide a completedescription of the manufacture and use of the disclosure. Since manyembodiments of the disclosure can be made without departing from thespirit and scope of the inventive aspects, the inventive aspects residesin the claims hereinafter appended.

What is claimed is:
 1. A telecommunications module comprising: a housingdefining an interior and including a first sidewall, a second sidewall,a top wall, a bottom wall, a rear wall, and a front wall, the housingextending in a longitudinal direction from the front wall toward therear wall; a first module input location positioned adjacent the frontwall of the housing and a second module input location positionedadjacent the front wall of the housing; a module output locationpositioned adjacent the front wall of the housing; an optical wavelengthdivision multiplexer/demultiplexer mounted within the interior of thehousing and having a multiplexer length extending generally parallel tothe longitudinal direction of the housing, the optical wavelengthdivision multiplexer/demultiplexer including a multiplexer inputlocation facing toward the rear wall and a multiplexer output locationfacing toward the front wall, the optical wavelength divisionmultiplexer/demultiplexer configured to demultiplex an optical signalinput into the telecommunications module via the first module inputlocation into a plurality of different wavelengths; a fiber opticsplitter mounted within the interior of the housing and having asplitter length extending generally parallel to the longitudinaldirection of the housing, the fiber optic splitter including a splitterinput location facing toward the front wall and a splitter outputlocation facing the rear wall, the fiber optic splitter configured tosplit an optical signal input into the telecommunication module via thesecond module input location into a plurality of signals; and aplurality of optical add/drop filters mounted within the interior of thehousing, each of the optical add/drop filters having a filter lengthextending generally parallel to the longitudinal direction of thehousing, each of the optical add/drop filters configured to combine oneof the signals that has been split by the fiber optic splitter and oneof the wavelengths that has been demultiplexed by the optical wavelengthdivision multiplexer/demultiplexer into a combination output signal thatis output by the telecommunications module through the module outputlocation, each optical add/drop filter including a first filter inputlocation facing toward the front wall, a second filter input locationfacing toward the rear wall, and a filter output location facing towardthe rear wall, the first filter input location configured to receive asignal from the fiber optic splitter and the second filter inputlocation configured to receive a signal from the optical wavelengthdivision multiplexer/demultiplexer.
 2. A telecommunications moduleaccording to claim 1, further comprising a first cable managementstructure located adjacent the rear wall for guiding cables extendingwithin the interior of the housing, the first cable management structureincluding a spool defining a curved wall.
 3. A telecommunications moduleaccording to claim 2, further comprising a second cable managementstructure located adjacent the front wall for guiding cables extendingwithin the interior of the housing, the second cable managementstructure including a curved wall.
 4. A telecommunications moduleaccording to claim 1, wherein the fiber optic splitter is a 1×8splitter, the optical wavelength division multiplexer/demultiplexer isan 8-channel multiplexer/demultiplexer, and the plurality of opticaladd/drop filters includes eight optical add/drop filters.
 5. Atelecommunications module according to claim 1, further including a topflange, a bottom flange, and a flexible latch adjacent the front wall,for slidable insertion into a telecommunications chassis.
 6. Atelecommunications module according to claim 1, further comprising cablesplice elements having lengths extending generally parallel to thelongitudinal direction of the housing, the splice elements being forsplicing cables extending between the optical wavelength divisionmultiplexer/demultiplexer and the optical add/drop filters and cablesextending between the fiber optic splitter and the optical add/dropfilters.
 7. A telecommunications module according to claim 1, whereinthe optical wavelength division multiplexer/demultiplexer, the fiberoptic splitter, and the optical add/drop filters are removably mountedwithin the housing, the telecommunications module further comprising aremovable cover to obtain access to the optical wavelength divisionmultiplexer/demultiplexer, the fiber optic splitter and the opticaladd/drop filters.
 8. A telecommunications module comprising: an opticalwavelength division multiplexer/demultiplexer configured to demultiplexa first optical signal input into the telecommunications module into aplurality of different wavelengths; a fiber optic splitter configured tosplit a second optical signal input into the telecommunication moduleinto a plurality of optical signals; and a plurality of optical add/dropfilters, each of the optical add/drop filters configured to combine oneof the optical signals that has been split by the fiber optic splitterand one of the wavelengths that has been demultiplexed by the opticalwavelength division multiplexer/demultiplexer into a combination outputsignal that is output from the telecommunications module.
 9. Atelecommunications module according to claim 8, wherein the fiber opticsplitter is a 1×8 splitter, the optical wavelength divisionmultiplexer/demultiplexer is an 8-channel multiplexer/demultiplexer, andthe plurality of optical add/drop filters includes eight opticaladd/drop filters.
 10. A telecommunications module according to claim 8,wherein the module is configured to be slidably inserted into atelecommunications chassis and interlock with the chassis with asnap-fit.
 11. A telecommunications module according to claim 8, furthercomprising cable splice elements for splicing cables extending betweenthe optical wavelength division multiplexer/demultiplexer and theoptical add/drop filters and cables extending between the fiber opticsplitter and the optical add/drop filters.
 12. A telecommunicationsmodule according to claim 8, wherein the optical wavelength divisionmultiplexer/demultiplexer, the fiber optic splitter, and the opticaladd/drop filters are removably mounted within the housing, thetelecommunications module further comprising a removable cover to obtainaccess to the optical wavelength division multiplexer/demultiplexer, thefiber optic splitter and the optical add/drop filters.